It's different for every gas. It also depends on the pressure.You actually need a two-dimensional depiction called a phasediagram. Check out the Wikipedia article on 'vapor'. You also needto consider that most substances will have a non-zero vaporpressure at temperatures below their boiling points and at leastdown to their freezing points. As long as you're not interested insome pedantic definition of gas which differentiates it from vapor,there is no specific temperature at which a gas turns to liquid, orvice versa.answ2. A gas turns into a liquid at its condensationtemperature, or in the reverse direction, a liquid turns into a gasat its boiling point.